Voyager fiddles with current->signal.tty without locking. It turns out
that the code in question has already cleared current->signal.tty
correctly because daemonize() does the right thing already.

The signal handling also appears to be incorrect as it does an
unprotected sigfillset that also appears unneccessary. As I don't have a
bowtie and am therefore not a qualified voyager maintainer I leave that
to James.